(1) Field of the Invention
The present invention relates to substrate processing apparatus for processing substrates such as semiconductor wafers and glass substrates for liquid crystal displays. More particularly, the invention relates to a coating technique for supplying a coating solution such as a photoresist solution to form a film of coating solution on substrates.
(2) Description of the Related Art
Drawbacks of the Prior Art:
(I) A series of coating processes for forming a film of photoresist, for example, on a substrate may broadly be divided into the following processes. A first process is a xe2x80x9ccoverage processxe2x80x9d for supplying a photoresist solution to the substrate to cover the entire surface of the substrate with the photoresist solution. A second process is a xe2x80x9cleveling processxe2x80x9d for making the photoresist solution on the substrate into a film. A third process is a xe2x80x9cdrying processxe2x80x9d for drying the film of photoresist solution formed on the substrate. A fourth process, carried out as necessary, is a xe2x80x9cremoving processxe2x80x9d for removing unwanted parts of the photoresist adhering to edges on the upper or front surface of the substrate having the film of photoresist formed thereon, and the photoresist adhering to the back surface of the substrate.
A conventional substrate processing apparatus having a coating unit carries out the above first to third processes or first to fourth processes consecutively with the single coating unit. Where, for example, a substrate processing apparatus has a spin coating unit for coating a substrate in a spin, the coating unit includes a spin chuck rotatable about a vertical axis while holding the substrate in horizontal posture, a coating solution supply nozzle for supplying a photoresist solution to the substrate held by the spin chuck, and a solvent supply nozzle for supplying a solvent to the back surface and edges of the substrate. The substrate processing apparatus having such a single coating unit consumes approximately 60 seconds in processing one substrate.
Incidentally, photoresists of the chemical amplification type that are becoming the mainline solution today are susceptible to the influence of a chemical contamination caused by atmospheric ammonia and the like. To minimize the time in which a substrate is exposed to atmosphere, the above substrate processing apparatus having the coating unit is connected with an exposing apparatus (i.e. stepper) that prints patterns on the substrate with a photoresist film formed thereon, to constitute an xe2x80x9cin-line systemxe2x80x9d widely employed for consecutively performing a series of operations from a coating process to an exposing process.
The exposing apparatus connected to the substrate processing apparatus consumes approximately 30 seconds in processing one substrate. To secure a throughput equal to that of the exposing apparatus, the conventional substrate processing apparatus is provided with a plurality of (e.g. two) coating units for carrying out the first to third processes (or first to fourth processes) concurrently.
The coating units of the conventional substrate processing apparatus must form photoresist films on substrates with an average film thickness and a thickness distribution within specified ranges. For this purpose, coating conditions such as resist discharge, resist temperature, and temperature and humidity within the coating unit are adjusted for each coating unit.
However, circuit patterns printed and developed on the substrates with the photoresist films formed thereon by the respective coating units show that serious variations in quality such as precision of the developed patterns occur among the substrates.
(II) Conventional substrate processing apparatus may have various coating units for performing a coating process by supplying a coating solution such as a photoresist solution to substrates. One such example is a thermal transfer type coating unit that first supplies a coating solution to an applicator sheet, applies the sheet to a substrate to supply the coating solution to the substrate, and separates the sheet from the substrate after heat treatment, thereby transferring a coating film from the sheet to the substrate. Another example is a scan type coating unit having a slit nozzle that discharges a coating solution while scanning or sweeping over a substrate maintained still, to supply the coating solution to the substrate. A third type of coating unit is what is known as a spin coater that supplies a coating solution adjacent the center of a substrate spinning at high speed, spreading the coating solution from the center of the substrate by the centrifugal force of the substrate to form a film of coating solution over the entire surface of the substrate.
A photolithographic procedure where the coating solution is a photoresist solution, for example, includes a series of processes such as (1) supplying the photoresist solution to the substrate to form a photoresist film on the substrate (coating process), (2) an exposing process for exposing the substrate coated with the photoresist film, and (3) developing the exposed substrate (developing process).
Usually, the coating process (1) and developing process (3) are carried out in the same substrate processing apparatus using a coating unit, while the exposing process (2) is carried out by an exposing apparatus which is an external processing apparatus associated with the substrate processing apparatus. Substrates are transferred between the substrate processing apparatus and exposing apparatus through an interface forming a part of the substrate processing apparatus.
However, such a conventional construction has the following drawbacks.
The substrate having undergone the coating process (1) could be exposed in a defective manner (i.e. defocused) in the exposing apparatus.
That is, where different positions on the surface of the substrate are at different heights from the lens of the exposing apparatus, the variations in the height could exceed the depth of focus of the lens, thereby causing a blur. This results in a defective exposure to affect the uniformity in line width of patterns obtained from the exposing process. Conventionally, such a defective exposure is considered due to particles adhering to the surface of the substrate, or ununiformity of the photoresist film formed on the substrate. To avoid the defective exposure, it is conventional practice to clean the surface of the substrate before the coating process or, in the case of a spin coater, adjust the spinning speed of the substrate to uniform the photoresist film. However, such surface cleaning alone has proved no ultimate solution to the defective exposure.
(III) Improved throughput in particular among the processing capabilities of the substrate processing apparatus is desired nowadays. For this purpose, measures have been taken not only to improve transport capability but to increase the number of processing units for performing the same series of processes in parallel.
FIG. 1 is a conceptual diagram of a parallel processing in which step A is carried out concurrently by using two processing units. Step A has a processing time of 60 seconds, for example. This apparatus has an improved throughput of 30 seconds owing to the parallel processing. However, such a technique of parallel processing relying on an increased number of processing units entails disadvantages of increased cost and enlargement of the apparatus.
A technique for overcoming such disadvantages has been proposed in Japanese Patent No. 3164739, for example. In the technique proposed in this patent, a process is divided to reduce the processing time consumed by each step, thereby to reduce the number of parallel processing units. Thus, throughput may be maintained while achieving a cost reduction and compactness of the apparatus. FIG. 2 is a conceptual diagram of an apparatus using such a technique. In this apparatus, step A is divided into step B (with a processing time of 30 seconds) and step C (with a processing time of 30 seconds) to be carried out in series by dedicated processing units, respectively. Thus, the process shown in FIG. 2 also has a throughput of 30 seconds as in the case shown in FIG. 1.
Each of the dedicated processing units used in such an apparatus may have a construction specialized for the intended process. Thus, while maintaining the same throughput, the apparatus construction may be simplified and reduced in size to achieve a cost reduction and the like. Since all substrates are processed by the same processing unit, less individual differences occur with final products.
However, the technique described in the above patent does not allow an equal processing time for the divided steps in an actual processing situation. The step consuming the longer time limits the throughput, resulting in a throughput reduction.
The present invention has been made having regard to the state of the art noted above, and its object is to provide a substrate processing apparatus for improving the throughput of substrate processing and checking quality variations among substrates, or for coating substrates with high precision and efficiently processing the substrates in combination with an external processing apparatus, or for avoiding a reduction in throughput even when part of processing consumes an extended time.
To overcome the disadvantage noted in section (I) above, Inventors have made intensive research and attained the following finding.
When exposing and developing conditions are set according to substrates processed by one coating unit, these substrates will be satisfactory in quality, but substrates processed by the other coating unit are found inferior in quality to the first-mentioned substrates. That is, the respective coating units must be in agreement as to various coating conditions in order to suppress quality variations among the substrates. In practice, however, the coating units have components with varied characteristics, which makes it difficult to bring the coating conditions of the coating units into strict agreement. Thus, instead of performing a parallel processing with a plurality of coating units, a series of film forming processes may be divided into separate time series, the divided processes being carried out successively by using a plurality of separate processing units. Based on this finding, the present invention provides the following construction.
A substrate processing apparatus, according to the invention, comprises a coating section for forming a film of coating solution on a substrate, wherein the coating section performs a series of film forming processes including a coverage process for supplying a coating solution to the substrate and covering a surface of the substrate with the coating solution, a leveling process for making the coating solution on the substrate into a film, and a drying process for drying the film of coating solution formed on the substrate, the coating section including a plurality of separate processing units for successively performing the series of film forming processes as divided into separate time series.
The substrate processing apparatus processes all substrates with the same coating conditions since a plurality of separate processing units are used for performing a series of film forming processes as divided into separate time series. This minimizes variations in quality among the substrates. Moreover, throughput may be improved since the processing units perform the divided processes concurrently.
The series of film forming processes may be divided in any way. For example, the plurality of separate processing units may include a coverage unit for performing the coverage process, and a leveling and drying unit for performing the leveling process and the drying process on the substrate processed by the coverage unit. The processing units may include a coverage and leveling unit for performing the coverage process and the leveling process, and a drying unit for performing the drying process on the substrate processed by the coverage and leveling unit. The processing units may include a coverage unit for performing the coverage process, a leveling unit for performing the leveling process on the substrate processed by the coverage unit, and a drying unit for performing the drying process on the substrate processed by the leveling unit.
The series of film forming processes may include a removing process for removing unwanted parts of the photoresist solution from the substrate, the coating section including a plurality of separate processing units for successively performing the series of film forming processes including the removing process as divided into separate time series.
The series of film forming processes including the above removing process may also be divided in any way. For example, the plurality of separate processing units may include a coverage unit for performing the coverage process, and a leveling, drying and removing unit for performing the leveling process, the drying process and the removing process. The processing units may include a coverage and leveling unit for performing the coverage process and the leveling process, and a drying and removing unit for performing the drying process and the removing process. The processing units may include a coverage, leveling and drying unit for performing the coverage process, the leveling process and the drying process, and a removing unit for performing the removing process. The processing units may include a coverage unit for performing the coverage process, a leveling unit for performing the leveling process, and a drying and removing unit for performing the drying process and the removing process. The processing units may include a coverage unit for performing the coverage process, a leveling and drying unit for performing the leveling process and the drying process, and a removing unit for performing the removing process. The processing units may include a coverage and leveling unit for performing the coverage process and the leveling process, a drying unit for performing the drying process, and a removing unit for performing the removing process. The processing units may include a coverage unit for performing the coverage process, a leveling unit for performing the leveling process, a drying unit for performing the drying process, and a removing unit for performing the removing process.
The removing process may be an edge rinsing for removing the film of coating solution from edges of the substrate, or a back rinsing for removing the coating solution from a back surface of the substrate.
In another aspect of the invention, a substrate processing apparatus comprises a coating section for forming a film of coating solution on a substrate, a developing section for developing the substrate after a coating process and an exposing process, a heat-treating section for heat-treating the substrate before and after the coating and developing processes, and a transport mechanism for transporting the substrate to each processing section, wherein the coating section performs a series of film forming processes including a coverage process for supplying a coating solution on the substrate and covering a surface of the substrate with the coating solution, a leveling process for making the coating solution on the substrate into a film, and a drying process for drying the film of coating solution formed on the substrate, the coating section including a plurality of separate processing units for successively performing the series of film forming processes as divided into separate time series.
With this substrate processing apparatus, a plurality of separate processing units successively perform a series of film forming processes as divided into separate time series. This stabilizes the quality of substrates, and improves the throughput of the substrate processing apparatus.
Preferably, the coating section further includes a dedicated transport mechanism for transporting the substrate between the plurality of separate processing units. In this case, the main transport mechanism of this substrate processing apparatus transports the substrate between the coating section, developing station and heat-treating section, and the dedicated transport mechanism is used to transport the substrate between the plurality of processing units in the coating section. That is, the dedicated transport mechanism undertakes to transport the substrate in the coating section, to avoid lowering of the throughput of the substrate processing apparatus due to an excessive burden falling on the main transport mechanism.
This specification discloses the following solution also:
(1) A substrate processing apparatus comprising a plurality of processing sections for performing predetermined processes on a substrate, a main transport mechanism for transporting the substrate between the processing sections, and a dedicated transport mechanism for transporting the substrate between certain of the processing sections in place of the main transport mechanism.
Where, for example, a substrate processing apparatus comprises a plurality of processing sections such as a coating section for forming a photoresist film on a substrate, a developing section for developing the substrate, and a heat-treating section for heat-treating the substrate, and a main transport mechanism used to transport the substrate between these processing sections, the transporting speed and substrate transfer speed of the main transport mechanism have upper limits although the processing efficiency of each processing section may be increased. Such upper limits may constrain the throughput of the substrate processing apparatus from being increased above a certain level. In the apparatus (1) noted above, the dedicated transport mechanism bears the duty of transporting the substrate between particular processing sections. This reduces the burden on the main transport mechanism, thereby improving the throughput of the substrate processing apparatus.
(2) A substrate processing apparatus as defined in (1) above, wherein the plurality of processing sections are arranged in vertical stages, the main transport mechanism being vertically movable for transporting the substrate at least between upper and lower processing sections, and the dedicated transport mechanism being used to transport the substrate between particular processing sections arranged at the same height.
With the apparatus (2) noted above, since the dedicated transport mechanism is used to transport the substrate between particular processing sections arranged at the same height, the substrate may be transported quickly between the particular processing sections. The dedicated transport mechanism may easily avoid interference with the main transport mechanism which moves vertically.
(3) A substrate processing apparatus as defined in (2) above, wherein the particular processing sections arranged at the same height are separate processing units for performing a series of film forming processes including a coverage process to supply a coating solution to substrate and cover a surface of the substrate with the coating solution, a leveling process for making the coating solution into a film on the substrate, and a drying process for drying the film of coating solution formed on the substrate, as divided into separate time series, the dedicated transport mechanism being used to transport the substrate between the separate processing units.
(4) A substrate processing apparatus as defined in (2) above, wherein the particular processing sections arranged at the same height are separate processing units for performing a series of film forming processes including a coverage process to supply a coating solution to substrate and cover a surface of the substrate with the coating solution, a leveling process for making the coating solution into a film on the substrate, a drying process for drying the film of coating solution formed on the substrate, and a removing process for removing unwanted parts of the coating solution from the substrate, as divided into separate time series, the dedicated transport mechanism being used to transport the substrate between the separate processing units.
With the apparatus (3) or (4) noted above, the dedicated transport mechanism transports the substrate between the plurality of processing units which perform the series of film forming processes as divided into separate time series. This reduces the burden on the main transport mechanism, and also avoids an inconvenience of contaminating other substrates with the coating solution adhering to the main transport mechanism as a result of transporting the substrate still in the course of forming a film.
To overcome the disadvantage noted in section (II) above, Inventors have made intensive research and obtained the following finding.
It has been thought heretofore that a cause of defective exposure is only on the front surface of a substrate. By thinking from a different angle, various experiments have been carried out on an assumption that a cause of defective exposure is also on the back surface of the substrate. The back surface of the substrate has been found to have unwanted parts of a coating solution having moved thereto when supplied to the front surface of the substrate, marks made when the back surface of the substrate is held by a suction type vacuum chuck in a process preceding an exposing process, or stains such as particles adhering to the back surface. It has been confirmed that defective exposure is reduced by removing such marks and stains from the back surface of the substrate. As a well-known technique of removing stains from the back surface of the substrate, for example, back rinsing may be carried out to deliver a cleaning solution from a nozzle opposite the back surface to wash the stains away from the back surface of the substrate. However, the coating processing and the cleaning process such as back rinsing noted above are carried out in series. There is a limitation to removal of stains from the back surface of the substrate by such a series processing. Further, stains may be transferred from a processed substrate to a support table on which the substrate is placed, and such stains may adhere even to a succeeding substrate to be processed. On the other hand, it is conceivable to improve the ability of removing stains adhering to the back surface of the substrate by regularly cleaning the substrate processing apparatus, particularly the support table in the coating section. However, this is a time-consuming operation involving moving of peripherals. To reduce the chance of defective exposure in the exposing process performed subsequently, the coating process and the cleaning process for removing stains from the back surface of the substrate may be performed separately. Based on this finding, the present invention provides the following construction.
A substrate processing apparatus, according to the invention, comprises a coating section including a first processing section for supplying a coating solution to a substrate, and a second processing section for supplying a cleaning solution to the substrate processed by the first processing section, wherein the first processing section includes a first substrate holding device for holding the substrate in horizontal posture while supporting a first support area on a back surface of the substrate, and a coating solution supplying device for supplying the coating solution to a front surface of the substrate held by the first substrate holding device; and the second processing section includes a second substrate holding device for holding the substrate in horizontal posture while supporting a second support area different from the first support area, and a cleaning solution supplying device for supplying the cleaning solution to clean a part or whole of the first support area on the back surface of the substrate held by the second substrate holding device.
With the substrate processing apparatus according to the invention, the first processing section is assigned with the coating process for supplying the coating solution from the coating solution supplying device to the front surface of the substrate to coat the front surface, and the second processing section is assigned with the cleaning process for supplying the cleaning solution from the cleaning solution supplying device to the back surface of the substrate to remove stains from the back surface of the substrate. Thus, the coating process and cleaning process are performed separately by the first and second processing sections, respectively. Further, the first processing section includes the first substrate holding device for holding the substrate in horizontal posture while supporting a first support area on the back surface of the substrate. The second processing section includes the second substrate holding device for holding the substrate in horizontal posture while supporting a second support area different from the first support area. The cleaning solution is supplied to clean a part or whole of the first support area on the back surface of the substrate held by the second substrate holding device. This improves the ability to remove stains from the back surface of the substrate. As a result, the substrate may be coated with high precision.
As a technique for the second substrate holding device to support the second support area different from the first support area, for example, the first substrate holding device may be constructed to hold the substrate in horizontal posture by supporting a central portion of the back surface of the substrate, and the second substrate holding device may be constructed to hold the substrate in horizontal posture by supporting edges of the substrate. Alternatively, the first substrate holding device may be constructed to hold the substrate in horizontal posture by supporting the first support area including a central portion of the back surface of the substrate, and the second substrate holding device may be constructed to hold the substrate in horizontal posture by supporting the second support area including the central portion of the back surface of the substrate.
To support the central portion of the back surface of the substrate, the first substrate holding device may be a vacuum chuck for holding the substrate in horizontal posture by suction-supporting the central portion of the back surface of the substrate.
As the latter technique, for example, the second substrate holding device may support the second support area different from the first support area, such that the first and second support areas are staggered relative to each other while including the central portion on the back surface of the substrate. Alternatively, the first and second substrate holding devices may be constructed such that the second support area is smaller than the first support area.
For the purpose of making the second support area smaller than the first support area, specifically, each of the first and second substrate holding devices may comprise a vacuum chuck for holding the substrate in horizontal posture by suction-supporting a central portion on the back surface of the substrate, the vacuum chuck acting as the second substrate holding device having a smaller diameter than the vacuum chuck acting as the first substrate holding device.
As a different technique for the second substrate holding device to support the second support area different from the first support area, for example, the first or second substrate holding device supports a plurality of locations (e.g. three locations) other than the central portion and edges. Alternatively, the substrate processing apparatus may further comprise a reversing device for turning over the substrate and placing the substrate back in position between the processes in the first and second processing sections, whereby the substrate is turned over by the reversing device so that the second substrate holding device holds the substrate in horizontal posture while supporting the second support area different from the first support area.
The cleaning process for removing stains from the substrate is not limited to the stains adhering to the back surface noted above, but may be applied to stains adhering, for example, to edges on the front surface of the substrate or to edges on the back surface of the substrate (e.g. edge rinsing). In the substrate processing apparatus according to the present invention, such edge cleaning process may be assigned to the first process section or second process section. For example, at least one of the first processing section and the second processing section may include an edge cleaning device for cleaning edges of the substrate.
In one preferred example of including the edge cleaning device in at least one of the first processing section and the second processing section, the edge cleaning device is disposed in the first processing section, the apparatus further comprising a first transport device for supporting the edges of the substrate and transporting the substrate between the first processing section and the second processing section, the first processing section performing a coating process on the front surface of the substrate, and an edge cleaning process for cleaning the edges of the substrate, the first transporting device transporting the substrate, after the coating process and the edge cleaning process, from the first processing section to the second processing section, and the second processing section performing a cleaning process for cleaning the part or whole of the first support area on the back surface of the substrate received from the first transport device.
The above feature is particularly useful with a transport device such as the first transport device that supports the edges of the substrate and transports the substrate between the first processing section and second processing section. That is, the first processing section first carries out the coating process for coating the surface of the substrate, and the edge rinsing process for removing stains from the edges of the substrate. Thus, no stains are present on the edges of the substrate when the first transport device supports the edges of the substrate and transports the substrate to the second processing section. Where the substrate is transported to the second processing section without carrying out the edge rinsing process in the first processing section to remove the stains from the edges of the substrate, the stains adhering to the edges of the substrate will not only adhere to the first transport device, but also affect, by staining, even the second processing section through the first transport device. The above construction effectively reduces contamination of the first transport device and the adverse effect on the second processing section.
In a further aspect of the invention, a substrate processing apparatus comprises a coating section for forming a film of coating solution on a substrate; wherein the coating section includes a first processing section for supplying a coating solution to the substrate, and a second processing section for supplying a cleaning solution to the substrate processed by the first processing section; the apparatus further comprising a second transport device for transporting the substrate between a plurality of processing sections including the first and second processing sections, the first processing section including a first substrate holding device for holding the substrate in horizontal posture while supporting a first support area on a back surface of the substrate, and a coating solution supplying device for supplying the coating solution to a front surface of the substrate held by the first substrate holding device; and the second processing section including a second substrate holding device for holding the substrate in horizontal posture while supporting a second support area different from the first support area, and a cleaning solution supplying device for supplying the cleaning solution to clean a part or whole of the first support area on the back surface of the substrate held by the second substrate holding device.
The above apparatus includes the second transport device for transporting the substrate between a plurality of processing sections including the first and second processing sections. This enables an efficient performance of a series of substrate processes including the coating process and the cleaning process for removing stains from the back surface of the substrate.
In a still further aspect of the invention, a substrate processing apparatus comprises a coating section for forming a film of coating solution on a substrate; wherein the coating section includes a first processing section for supplying a coating solution to the substrate, and a second processing section for supplying a cleaning solution to the substrate processed by the first processing section; the apparatus further comprising a second transport device for transporting the substrate between a plurality of processing sections including the first and second processing sections, an external processing apparatus connected to the substrate processing apparatus, and an interface for relaying transfer of the substrate between the processing sections and the external processing apparatus; the first processing section including a first substrate holding device for holding the substrate in horizontal posture while supporting a first support area on a back surface of the substrate, and a coating solution supplying device for supplying the coating solution to a front surface of the substrate held by the first substrate holding device; and the second processing section including a second substrate holding device for holding the substrate in horizontal posture while supporting a second support area different from the first support area, and a cleaning solution supplying device for supplying the cleaning solution to clean a part or whole of the first support area on the back surface of the substrate held by the second substrate holding device.
The above apparatus includes the external processing apparatus connected to the substrate processing apparatus, and the interface for relaying transfer of the substrate between the processing sections and the external processing apparatus. The substrate coated with high precision in the coating section is transported through the interface to the external processing apparatus. Since the substrate is coated with high precision, the substrate processing may be performed efficiently in the external processing apparatus.
The external processing apparatus may be an exposing apparatus for exposing the substrate after a coating process. Where the external processing apparatus is an exposing apparatus, since the substrate is coated with high precision in the coating section, defective exposure due to stains adhering to the back surface of the substrate may be reduced, compared with the prior art.
The above apparatus overcomes the disadvantage noted in section (II) above, that is to remove stains from the back surface of the substrate. However, the cleaning solution may be applied only to the back surface of the substrate. Unless the cleaning solution is applied to peripheral surfaces of the substrate, stains adhering to the peripheral surfaces may not be removed therefrom. This specification discloses a substrate processing apparatus different from the above apparatus, based on the above finding, to remove stains from the peripheral surfaces of the substrate efficiently, as follows:
(5) A substrate processing apparatus comprising a coating section including a third processing section for supplying a coating solution to a substrate, and a second processing section for supplying a cleaning solution to the substrate processed by the first processing section, wherein the third processing section includes a third substrate holding device for holding the substrate in horizontal posture while supporting peripheral surfaces of the substrate, and a coating solution supplying device for supplying the coating solution to a front surface of the substrate held by the third substrate holding device; and the second processing section includes a second substrate holding device for holding the substrate in horizontal posture while supporting areas different from the peripheral surfaces of the substrate supported by the third substrate holding device, and a cleaning solution supplying device for supplying the cleaning solution to clean at least the peripheral surfaces of the substrate supported by the third substrate holding device.
In the foregoing apparatus for overcoming the disadvantage (II), the back surface of the substrate may be replaced with the peripheral surfaces of the substrate, that is the construction as set forth in the invention (5) above, stains may be removed from the peripheral surfaces of the substrate. The term xe2x80x9cperipheral surfaces of the substratexe2x80x9d used herein is intended to mean vertical surfaces, or side surfaces, bridging the front surface and back surface which are horizontal surfaces. The term xe2x80x9cedges of the substratexe2x80x9d is intended to mean edges of the front surface and back surface including the peripheral surfaces of the substrate.
To overcome the disadvantage (III) noted hereinbefore, the present invention provides a substrate processing apparatus comprising a plurality of processing units for performing one stage of operation in which a processing object is in form of a particular substance on a substrate or in a particular form of energy relating to the substrate, the one stage being divided into a plurality of processes each involving an increase or decrease of the processing object; and a transport mechanism for transporting the substrate to the plurality of processing units; at least the processing units including a plurality of first partial processing units, and a second partial processing unit for performing a partial process having a shorter processing time than a process performed by each of the first partial processing units; the plurality of first partial processing units performing a parallel processing.
Generally, the plurality of processing units in the present invention share processes involving an increase or decrease of xe2x80x9cprocessing objectsxe2x80x9d, and a chain of such processes constitutes one stage. The xe2x80x9cprocessing objectsxe2x80x9d here include a xe2x80x9cchemicalxe2x80x9d in a xe2x80x9cchemical processxe2x80x9d, xe2x80x9cheatxe2x80x9d in a xe2x80x9cheat treatmentxe2x80x9d (heating and cooling), xe2x80x9cforeign mattersxe2x80x9d in a xe2x80x9ccleaning processxe2x80x9d, xe2x80x9cmoisturexe2x80x9d on wafers in a xe2x80x9cdrying processxe2x80x9d, and a xe2x80x9clayer to be exposedxe2x80x9d in an xe2x80x9cexposing processxe2x80x9d.
With the substrate processing apparatus according to the invention, a plurality of processing units perform one stage of operation in which a processing object is in form of a particular substance on a substrate or in a particular form of energy relating to the substrate, the one stage being divided into a plurality of processes performed concurrently and each involving an increase or decrease of the processing object. This feature can avoid throughput being limited by a process requiring a long processing time where a difference in processing time occurs between the partial processing units.
For example, the processing object may be a chemical applied to the substrate, the first partial processing units performing a chemical coating process on the substrate. Then, throughput may be maintained even where, with the increase in substrate size, the chemical coating process tends to require an extended processing time. Particularly where the chemical is a resist, throughput may be maintained for a resist coating process which forms an important part of substrate processing.
In one preferred example of chemical coating process, the second partial processing unit performs a rinsing process including a back rinsing process for removing the chemical from the substrate. With the second partial processing unit performing the rinsing process including the back rinsing process, the other processing units may be simplified. Preferably, each of the first partial processing units and the second partial processing unit has a spin chuck for holding and spinning the substrate, the spin chuck of the second partial processing unit being smaller in diameter than the spin chuck of each of the first partial processing units. Since the spin chuck of the second partial processing unit is smaller than the spin chuck of each of the first partial processing units, particles having adhered to the back surface in each first partial processing unit may be washed away in the larger quantity for the smaller chuck, to reduce particles on the back surface.
Similarly, it is preferred in performing the chemical coating process that each of the first partial processing units performs a first edge rinsing process for edges of the substrate coated with the chemical. With each of the first partial processing units performing the first edge rinsing process for edges of the substrate coated with the chemical, a defective transport may be prevented from occurring when the substrate is transported from each of the first partial processing units. Preferably, the rinsing process includes a second edge rinsing process, the first edge rinsing process covering a smaller range on the substrate than the second edge rinsing process. With this feature, the edge rinsing function of each first processing unit is simplified to simplify the construction of the first processing unit.
In another preferred embodiment for performing the chemical coating process, the substrate processing apparatus further comprises a device for controlling at least one of temperature and humidity only in a space accommodating the first partial processing units, to be within a predetermined range. This apparatus has a simplified construction compared with the case of controlling the temperature and humidity of all the spaces in the apparatus.
In a further preferred embodiment for performing the chemical coating process, the substrate processing apparatus further comprises a chemical nozzle for delivering the chemical, the plurality of first partial processing units sharing the chemical nozzle. With the chemical nozzle shared by the plurality of first partial processing units, there is no need to provide a chemical nozzle for each first partial processing unit. Thus, the apparatus may be reduced in cost, while reducing individual differences among the substrates manufactured.
In the substrate processing apparatus for overcoming the disadvantage (III) noted above, it is preferred that the plurality of first partial processing units are spatially isolated on a basis of processing units performing the same process, at least during the process. With this construction, the substrate processed in each first processing unit is prevented from being affected by other processes performed separately.